Gas–solid interactions with reactive and inert gas molecules by NAPUPS: can work function be a better descriptor of chemical reactivity?

Ghosalya, Manoj Kumar; Reddy, Kasala Prabhakar; Mhamane, Nitin B.; Ranjan, Ravi; Gopinath, Chinnakonda S.

doi:10.1039/d0cp02456b

Cited by 7 publications

(12 citation statements)

References 40 publications

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“…The energy gap between successive lines and why it is different from the corresponding stretching frequency is discussed in detail in the Supporting Information (S4). A similar aspect has been discussed for N 2 , H 2 , and O 2 in our earlier work. , …”

Section: Resultssupporting

confidence: 79%

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Sustainable CO₂ Reduction on In₂O₃ with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Mhamane

Chetry

Ranjan

et al. 2022

ACS Sustainable Chem. Eng.

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This study demonstrates a sustainable catalytic CO2 conversion to near 100% CO selectivity at ambient pressure on In2O3. Critically, high CO yield could be observed at the cost of undesired methanation, using a lower than stoichiometric amount of hydrogen in the feed; 1:1 and 1:0.67 CO2:H2 ratios exhibit 98–99.6% CO selectivity with 25–38% CO2 conversion between 773 and 873 K. CO2 and H2 conversion under steady-state conditions at 773–873 K suggests a 1:1 ratio of adsorbed reactants (with 1:0.67 CO2:H2 feed) on the catalyst surface, underscoring the presence of an ideal reactant composition for the reverse water-gas shift reaction, while H2-rich feed compositions show the H2-dominated surface. Surface electronic structure changes, under near-operating conditions, were explored with near ambient pressure photoelectron spectroscopy (NAPPES), and the interesting findings are as follows: (a) A shift in the valence band to lower binding energy, up to 0.6 eV, was observed because of electron filling at high temperatures. (b) An observation of heterogeneous nature of the catalyst surface under NAPPES measurement conditions is attributed to the generation of active oxygen vacancy (Ov) sites, which in turn changes the work function of In2O3. (c) The above changes are found to be reversible, when the reaction was stopped. Vibrational features of the reactant molecules were observed to be broadened in the active temperature window of the catalyst supporting the heterogeneous character of the catalyst surface because of dynamic Ov generation. By optimizing gas hourly space velocity, CO2:H2 ratio, and reaction temperature, exclusive CO selectivity is possible with a H2:CO2 ratio of ∼0.67, which will avoid the product separation stage altogether, while minimizing the expensive H2 in the reactant feed.

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Section: Resultssupporting

confidence: 79%

“…A similar aspect has been discussed for N 2 , H 2 , and O 2 in our earlier work. 44,45 A simple comparison of the gas-phase spectrum of CO 2 and H 2 molecules and the same on the In 2 O 3 surface at 295 K reveals a significant shift in the latter. The shift observed is attributed to the work function (ϕ) of the In 2 O 3 surface.…”

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confidence: 99%

Sustainable CO₂ Reduction on In₂O₃ with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Mhamane

Chetry

Ranjan

et al. 2022

ACS Sustainable Chem. Eng.

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“…Compared to the virgin Pd NC , the Pt-coating on it leading to an enhancement in intensity suggests a change in ϕ and possible electron transfer from Pd to Pt. Indeed the lower BE shift (up to 0.5 eV) observed in metallic Pt 4f core levels (Figure ) fully supports the role of charge transfer and ϕ changes . Nonetheless, a 0.2 eV shift is observed with the Pt coating on Pd TO , and the intensity is similar to Pd NC at 1 eV.…”

Section: Resultssupporting

confidence: 67%

“…Indeed the lower BE shift (up to 0.5 eV) observed in metallic Pt 4f core levels (Figure 6) fully supports the role of charge transfer and ϕ changes. 63 Nonetheless, a 0.2 eV shift is observed with the Pt coating on Pd TO , and the intensity is similar to Pd NC at 1 eV. It is also to be noted that the broadening observed on the higher BE side of 0.5θ Pt -Pd TO is likely due to some residual impurities (chloride and PVP), which were difficult to remove.…”

Section: Acs Applied Energy Materialsmentioning

confidence: 86%

Aqueous Methanol to Formaldehyde and Hydrogen on Pd/TiO₂ by Photocatalysis in Direct Sunlight: Structure Dependent Activity of Nano-Pd and Atomic Pt-Coated Counterparts

Nalajala

Salgaonkar

Chauhan

et al. 2021

ACS Appl. Energy Mater.

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In the present investigation, facet-controlled Pd nanoparticles with nanocube (PdNC) and truncated octahedron (PdTO) morphologies, and their counterparts with half-a-monolayer of atomic Pt coated (0.5θPt-PdNC and 0.5θPt-PdTO) surfaces were prepared. All of them were characterized and evaluated as cocatalyst after supporting them on commercial titania (P25) (PdNC/P25, PdTO/P25, 0.5θPt-PdNC/P25, and 0.5θPt-PdTO/P25) under direct sunlight and/or one sun conditions for the oxidation of methanol to formaldehyde along with solar hydrogen production. PdNC/P25 shows higher activity for hydrogen generation compared to PdTO/P25; however, activity reversal occurs with the above cocatalysts, but, after Pt-coating with further enhanced activity. The highest conversion of methanol (0.2 μmol/h.mg) to 100% selective formaldehyde was observed with 0.5θPt-PdTO/P25, while other catalysts show significantly lower methanol conversion in the following order: 0.5θPt-PdTO/P25 > 0.5θPt-PdNC/P25 > PdNC/P25 > PdTO/P25. Pt-coated on (111) facets of PdTO simulates the activity associated as that of Pt(111) facets and demonstrating the highest and facet dependent activity. The present study is truly in resonance with exploiting the surface properties for heterogeneous catalysis, and highlights that less than a monolayer of Pt is sufficient to simulate the activity as that of bulk Pt. It is worth exploring this concept to other metals and substrates too.

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“…It is well-known that shift in CB energy would enhance the electron utilization and HER. VBPES analysis fully ascertain a strong electronic interaction between titania and the cocatalyst, particularly in NFT31. − …”

Section: Resultsmentioning

confidence: 98%

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Tudu

Nalajala

Reddy

et al. 2021

ACS Sustainable Chem. Eng.

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Developing highly efficient and affordable catalysts for solar hydrogen (H2) generation is crucial, and employing a cocatalyst from earth-abundant elements has a critical role to play. In this context, different compositions of earth-abundant Ni–Fe alloy (1:1, 1:3, and 3:1) have been prepared by hydrothermal method; subsequently, 1 wt % of these Ni–Fe cocatalysts were integrated with TiO2-P25 and thoroughly characterized. The resultant catalysts have been evaluated for solar H2 production, in powder and thin film forms, under one sun condition and in direct sunlight. Interestingly, all the catalysts in the thin film form exhibit superior hydrogen yield (HY), up to 27 times higher activity than its powder counterpart. Among the photocatalysts, Ni–Fe/TiO2 (3:1 = Ni/Fe; NFT31) composition exhibits the best HY in thin film (8.27 mmol·h–1·g–1) and exceeds all other compositions of catalyst. It is also to be reported that HY measured for the powder form with 1 mg shows 3–17 times higher activity than that measured with 25 mg. This is mainly attributed to effective solar light absorption with a smaller amount of photocatalyst either spread over large area in a thin film form or well-dispersed in suspension forms. Furthermore, the enhanced activity obtained with Ni–Fe/TiO2 photocatalysts is also ascribed to strong electronic integration of Ni–Fe cocatalyst with TiO2 and higher performance obtained with a thin film is attributed to increased charge carrier generation and subsequent charge separation and effective utilization. A decrease in work function of TiO2 by 0.6 eV was observed after its integration with cocatalyst in NFT31.

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Gas–solid interactions with reactive and inert gas molecules by NAPUPS: can work function be a better descriptor of chemical reactivity?

Abstract:
Work function alteration due to any chemical/electronic changes can be measured precisely by NAPUPS and correlated to the activity changes.

Cited by 7 publications

References 40 publications

Sustainable CO₂ Reduction on In₂O₃ with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Sustainable CO₂ Reduction on In₂O₃ with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Aqueous Methanol to Formaldehyde and Hydrogen on Pd/TiO₂ by Photocatalysis in Direct Sunlight: Structure Dependent Activity of Nano-Pd and Atomic Pt-Coated Counterparts

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

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Gas–solid interactions with reactive and inert gas molecules by NAPUPS: can work function be a better descriptor of chemical reactivity?

Abstract: Work function alteration due to any chemical/electronic changes can be measured precisely by NAPUPS and correlated to the activity changes.

Cited by 7 publications

References 40 publications

Sustainable CO2 Reduction on In2O3 with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Sustainable CO2 Reduction on In2O3 with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Aqueous Methanol to Formaldehyde and Hydrogen on Pd/TiO2 by Photocatalysis in Direct Sunlight: Structure Dependent Activity of Nano-Pd and Atomic Pt-Coated Counterparts

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

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Product

Resources

About

Abstract:
Work function alteration due to any chemical/electronic changes can be measured precisely by NAPUPS and correlated to the activity changes.

Sustainable CO₂ Reduction on In₂O₃ with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Sustainable CO₂ Reduction on In₂O₃ with Exclusive CO Selectivity: Catalysis and In Situ Valence Band Photoelectron Spectral Investigations

Aqueous Methanol to Formaldehyde and Hydrogen on Pd/TiO₂ by Photocatalysis in Direct Sunlight: Structure Dependent Activity of Nano-Pd and Atomic Pt-Coated Counterparts